We continue our chart of the progression of Ebola in West Africa,
originally introduced in Chronology
of the Ebola Outbreak in West
Africa. Six weeks of data are added to the last rendition of the
Chart 5, bringing us to Jan 20, 2015. Data is taken from the
regular online WHO updates and the last update on or before each data
point date is used.
The plots for Sierra Leone and Guinea reflect laboratory confirmed
cases of Ebola only. For Liberia, however, because initially many cases
were not confirmed by lab test, the plot is of total
cases, comfirmed, probable and suspect.
Trend lines were developed in Ebola
Chart 3 to predict the course of
the outbreak in each country up to the end of the year. The trend lines
were developed using data up to Sept. 2. These trendlines are
reproduced here, but with the new data points since Sept. 2 included.
The trendlines shown are the original ones and have NOT been
recomputed using newer data. Thus, they reflect our best guess of the
progression of the disease on Sept. 2. In most cases the outbreak has
been even more severe than we predicted. The "worst case" scenario for
Liberia, an exponential expansion of the outbreak, thankfully was not
The three curves clearly show a flattening in the most recent data,
reflecting the slowing of the outbreak. The chart shows
Liberia total (suspect, probable and confirmed) cases, whilst only
confirmed cases are plotted for Guinea and Sierra Leone. This is
because of inadequate testing capacity in Liberia at the start of the
outbreak. The jagged nature of particularly the Liberia curve, reflects
problems with data collection and assessment rather than actual
variations in infection rates.
The chart above shows the trend line computed on Sept. 2 for Sierra
Leone and the actual data points collected since then. The new data
shows that Sierra Leone's infection rate has consistently exceeded the
trend predicted on Sept. 2. There is no indication from the chart of
any marked effect of either the Sept. 19 'ose to ose" campaign or the
December 17 Operation Surge.
The chart above shows the trend line computed on Sept. 2 for
Guinea and the actual data points collected since then. The
new data shows that Guinea's infection rate, while still lower than the
other two countries, has exceeded the initial early trend. The
data continues to show a marked increase in the infection rate starting
around the end of August.
The chart above shows the less pessimistic trend line
on Sept. 2 (see Ebola
Chart 3) for Liberia and the actual data points collected since